volume | PIER Journals

Abstract

To address the issue of significant torque ripple in traditional direct instantaneous torque control strategies for permanent magnet assisted switched reluctance motors, which stems from the use of fixed hysteresis thresh-olds, this paper proposes a variable hysteresis threshold pulse width modulation (PWM) method based on subdivided regions. First, based on the torque-current ratio curve features, the two-phase exchange (TpE) region is subdivided into two-phase exchange I (TpE I) and two-phase exchange II (TpE II), using the angle of equal torque-current ratio as the dividing point. PWM control was applied within these two intervals to ensure a smoother transition of the total torque during commutation. Second, the hysteresis threshold is optimized by a BP neural network tuned via the dung beetle optimizer (DBO) algorithm under different speeds and loads, thereby enhancing the system's flexibility. Finally, simulations and experiments were performed using a 6/20 three phases permanent magnet-assisted switched reluctance motor. Experimental results show that the torque ripple is reduced from 30.4% to 11% under 500 r/min and 5 N.m, and PWM with a variable hysteresis threshold can effectively suppress torque ripple.

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Dr. Junwu Zhu

Dr. Junxin Xu

Dr. Yan Chen